You access the mini game by right-clicking a number of times.

When the mini game pops up. You need to kill 42 flies.

Do this by staying in the middle of the screen and shooting the flies quickly.

If you have shot a few flies and have an empty screen then shoot the rest of your bullets quickly to get a reload jellybean.

Move slowly unless you need to quickly get the jellybean then use the space bar to sprint.

The game slowly gets harder and if you use R to restart after dying it quickly becomes impossible.

After losing press rightclick to exit the game and then right-click to go back into the game and this will reset the difficultly back to easy.